/*
** $Id: lparser.c,v 2.130 2013/02/06 13:37:39 roberto Exp $
** Lua Parser
** See Copyright Notice in lua.h
*/


#include <string.h>

#define lparser_c
#define LUA_CORE

#include "lua.h"

#include "lcode.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "llex.h"
#include "lmem.h"
#include "lobject.h"
#include "lopcodes.h"
#include "lparser.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"



/* maximum number of local variables per function (must be smaller
than 250, due to the bytecode format) */
#define MAXVARS		200


#define hasmultret(k)		((k) == VCALL || (k) == VVARARG)



/*
** nodes for block list (list of active blocks)
*/
typedef struct BlockCnt {
	struct BlockCnt *previous;  /* chain */
	short firstlabel;  /* index of first label in this block */
	short firstgoto;  /* index of first pending goto in this block */
	lu_byte nactvar;  /* # active locals outside the block */
	lu_byte upval;  /* true if some variable in the block is an upvalue */
	lu_byte isloop;  /* true if `block' is a loop */
} BlockCnt;



/*
** prototypes for recursive non-terminal functions
*/
static void statement (LexState *ls);
static void expr (LexState *ls, expdesc *v);


static void anchor_token (LexState *ls) {
	/* last token from outer function must be EOS */
	lua_assert(ls->fs != NULL || ls->t.token == TK_EOS);
	if (ls->t.token == TK_NAME || ls->t.token == TK_STRING) {
		TString *ts = ls->t.seminfo.ts;
		luaX_newstring(ls, getstr(ts), ts->tsv.len);
	}
}


/* semantic error */
static l_noret semerror (LexState *ls, const char *msg) {
	ls->t.token = 0;  /* remove 'near to' from final message */
	luaX_syntaxerror(ls, msg);
}


static l_noret error_expected (LexState *ls, int token) {
	luaX_syntaxerror(ls,
		luaO_pushfstring(ls->L, "%s expected", luaX_token2str(ls, token)));
}


static l_noret errorlimit (FuncState *fs, int limit, const char *what) {
	lua_State *L = fs->ls->L;
	const char *msg;
	int line = fs->f->linedefined;
	const char *where = (line == 0)
		? "main function"
		: luaO_pushfstring(L, "function at line %d", line);
	msg = luaO_pushfstring(L, "too many %s (limit is %d) in %s",
		what, limit, where);
	luaX_syntaxerror(fs->ls, msg);
}


static void checklimit (FuncState *fs, int v, int l, const char *what) {
	if (v > l) errorlimit(fs, l, what);
}


static int testnext (LexState *ls, int c) {
	if (ls->t.token == c) {
		luaX_next(ls);
		return 1;
	}
	else return 0;
}


static void check (LexState *ls, int c) {
	if (ls->t.token != c)
		error_expected(ls, c);
}


static void checknext (LexState *ls, int c) {
	check(ls, c);
	luaX_next(ls);
}


#define check_condition(ls,c,msg)	{ if (!(c)) luaX_syntaxerror(ls, msg); }



static void check_match (LexState *ls, int what, int who, int where) {
	if (!testnext(ls, what)) {
		if (where == ls->linenumber)
			error_expected(ls, what);
		else {
			luaX_syntaxerror(ls, luaO_pushfstring(ls->L,
				"%s expected (to close %s at line %d)",
				luaX_token2str(ls, what), luaX_token2str(ls, who), where));
		}
	}
}


static TString *str_checkname (LexState *ls) {
	TString *ts;
	check(ls, TK_NAME);
	ts = ls->t.seminfo.ts;
	luaX_next(ls);
	return ts;
}


static void init_exp (expdesc *e, expkind k, int i) {
	e->f = e->t = NO_JUMP;
	e->k = k;
	e->u.info = i;
}


static void codestring (LexState *ls, expdesc *e, TString *s) {
	init_exp(e, VK, luaK_stringK(ls->fs, s));
}


static void checkname (LexState *ls, expdesc *e) {
	codestring(ls, e, str_checkname(ls));
}


static int registerlocalvar (LexState *ls, TString *varname) {
	FuncState *fs = ls->fs;
	Proto *f = fs->f;
	int oldsize = f->sizelocvars;
	luaM_growvector(ls->L, f->locvars, fs->nlocvars, f->sizelocvars,
		LocVar, SHRT_MAX, "local variables");
	while (oldsize < f->sizelocvars) f->locvars[oldsize++].varname = NULL;
	f->locvars[fs->nlocvars].varname = varname;
	luaC_objbarrier(ls->L, f, varname);
	return fs->nlocvars++;
}


static void new_localvar (LexState *ls, TString *name) {
	FuncState *fs = ls->fs;
	Dyndata *dyd = ls->dyd;
	int reg = registerlocalvar(ls, name);
	checklimit(fs, dyd->actvar.n + 1 - fs->firstlocal,
		MAXVARS, "local variables");
	luaM_growvector(ls->L, dyd->actvar.arr, dyd->actvar.n + 1,
		dyd->actvar.size, Vardesc, MAX_INT, "local variables");
	dyd->actvar.arr[dyd->actvar.n++].idx = cast(short, reg);
}


static void new_localvarliteral_ (LexState *ls, const char *name, size_t sz) {
	new_localvar(ls, luaX_newstring(ls, name, sz));
}

#define new_localvarliteral(ls,v) \
	new_localvarliteral_(ls, "" v, (sizeof(v)/sizeof(char))-1)


static LocVar *getlocvar (FuncState *fs, int i) {
	int idx = fs->ls->dyd->actvar.arr[fs->firstlocal + i].idx;
	lua_assert(idx < fs->nlocvars);
	return &fs->f->locvars[idx];
}


static void adjustlocalvars (LexState *ls, int nvars) {
	FuncState *fs = ls->fs;
	fs->nactvar = cast_byte(fs->nactvar + nvars);
	for (; nvars; nvars--) {
		getlocvar(fs, fs->nactvar - nvars)->startpc = fs->pc;
	}
}


static void removevars (FuncState *fs, int tolevel) {
	fs->ls->dyd->actvar.n -= (fs->nactvar - tolevel);
	while (fs->nactvar > tolevel)
		getlocvar(fs, --fs->nactvar)->endpc = fs->pc;
}


static int searchupvalue (FuncState *fs, TString *name) {
	int i;
	Upvaldesc *up = fs->f->upvalues;
	for (i = 0; i < fs->nups; i++) {
		if (luaS_eqstr(up[i].name, name)) return i;
	}
	return -1;  /* not found */
}


static int newupvalue (FuncState *fs, TString *name, expdesc *v) {
	Proto *f = fs->f;
	int oldsize = f->sizeupvalues;
	checklimit(fs, fs->nups + 1, MAXUPVAL, "upvalues");
	luaM_growvector(fs->ls->L, f->upvalues, fs->nups, f->sizeupvalues,
		Upvaldesc, MAXUPVAL, "upvalues");
	while (oldsize < f->sizeupvalues) f->upvalues[oldsize++].name = NULL;
	f->upvalues[fs->nups].instack = (v->k == VLOCAL);
	f->upvalues[fs->nups].idx = cast_byte(v->u.info);
	f->upvalues[fs->nups].name = name;
	luaC_objbarrier(fs->ls->L, f, name);
	return fs->nups++;
}


static int searchvar (FuncState *fs, TString *n) {
	int i;
	for (i = cast_int(fs->nactvar) - 1; i >= 0; i--) {
		if (luaS_eqstr(n, getlocvar(fs, i)->varname))
			return i;
	}
	return -1;  /* not found */
}


/*
Mark block where variable at given level was defined
(to emit close instructions later).
*/
static void markupval (FuncState *fs, int level) {
	BlockCnt *bl = fs->bl;
	while (bl->nactvar > level) bl = bl->previous;
	bl->upval = 1;
}


/*
Find variable with given name 'n'. If it is an upvalue, add this
upvalue into all intermediate functions.
*/
static int singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) {
	if (fs == NULL)  /* no more levels? */
		return VVOID;  /* default is global */
	else {
		int v = searchvar(fs, n);  /* look up locals at current level */
		if (v >= 0) {  /* found? */
			init_exp(var, VLOCAL, v);  /* variable is local */
			if (!base)
				markupval(fs, v);  /* local will be used as an upval */
			return VLOCAL;
		}
		else {  /* not found as local at current level; try upvalues */
			int idx = searchupvalue(fs, n);  /* try existing upvalues */
			if (idx < 0) {  /* not found? */
				if (singlevaraux(fs->prev, n, var, 0) == VVOID) /* try upper levels */
					return VVOID;  /* not found; is a global */
				/* else was LOCAL or UPVAL */
				idx  = newupvalue(fs, n, var);  /* will be a new upvalue */
			}
			init_exp(var, VUPVAL, idx);
			return VUPVAL;
		}
	}
}


static void singlevar (LexState *ls, expdesc *var) {
	TString *varname = str_checkname(ls);
	FuncState *fs = ls->fs;
	if (singlevaraux(fs, varname, var, 1) == VVOID) {  /* global name? */
		expdesc key;
		singlevaraux(fs, ls->envn, var, 1);  /* get environment variable */
		lua_assert(var->k == VLOCAL || var->k == VUPVAL);
		codestring(ls, &key, varname);  /* key is variable name */
		luaK_indexed(fs, var, &key);  /* env[varname] */
	}
}


static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) {
	FuncState *fs = ls->fs;
	int extra = nvars - nexps;
	if (hasmultret(e->k)) {
		extra++;  /* includes call itself */
		if (extra < 0) extra = 0;
		luaK_setreturns(fs, e, extra);  /* last exp. provides the difference */
		if (extra > 1) luaK_reserveregs(fs, extra-1);
	}
	else {
		if (e->k != VVOID) luaK_exp2nextreg(fs, e);  /* close last expression */
		if (extra > 0) {
			int reg = fs->freereg;
			luaK_reserveregs(fs, extra);
			luaK_nil(fs, reg, extra);
		}
	}
}


static void enterlevel (LexState *ls) {
	lua_State *L = ls->L;
	++L->nCcalls;
	checklimit(ls->fs, L->nCcalls, LUAI_MAXCCALLS, "C levels");
}


#define leavelevel(ls)	((ls)->L->nCcalls--)


static void closegoto (LexState *ls, int g, Labeldesc *label) {
	int i;
	FuncState *fs = ls->fs;
	Labellist *gl = &ls->dyd->gt;
	Labeldesc *gt = &gl->arr[g];
	lua_assert(luaS_eqstr(gt->name, label->name));
	if (gt->nactvar < label->nactvar) {
		TString *vname = getlocvar(fs, gt->nactvar)->varname;
		const char *msg = luaO_pushfstring(ls->L,
			"<goto %s> at line %d jumps into the scope of local " LUA_QS,
			getstr(gt->name), gt->line, getstr(vname));
		semerror(ls, msg);
	}
	luaK_patchlist(fs, gt->pc, label->pc);
	/* remove goto from pending list */
	for (i = g; i < gl->n - 1; i++)
		gl->arr[i] = gl->arr[i + 1];
	gl->n--;
}


/*
** try to close a goto with existing labels; this solves backward jumps
*/
static int findlabel (LexState *ls, int g) {
	int i;
	BlockCnt *bl = ls->fs->bl;
	Dyndata *dyd = ls->dyd;
	Labeldesc *gt = &dyd->gt.arr[g];
	/* check labels in current block for a match */
	for (i = bl->firstlabel; i < dyd->label.n; i++) {
		Labeldesc *lb = &dyd->label.arr[i];
		if (luaS_eqstr(lb->name, gt->name)) {  /* correct label? */
			if (gt->nactvar > lb->nactvar &&
				(bl->upval || dyd->label.n > bl->firstlabel))
				luaK_patchclose(ls->fs, gt->pc, lb->nactvar);
			closegoto(ls, g, lb);  /* close it */
			return 1;
		}
	}
	return 0;  /* label not found; cannot close goto */
}


static int newlabelentry (LexState *ls, Labellist *l, TString *name,
						  int line, int pc) {
							  int n = l->n;
							  luaM_growvector(ls->L, l->arr, n, l->size,
								  Labeldesc, SHRT_MAX, "labels/gotos");
							  l->arr[n].name = name;
							  l->arr[n].line = line;
							  l->arr[n].nactvar = ls->fs->nactvar;
							  l->arr[n].pc = pc;
							  l->n++;
							  return n;
}


/*
** check whether new label 'lb' matches any pending gotos in current
** block; solves forward jumps
*/
static void findgotos (LexState *ls, Labeldesc *lb) {
	Labellist *gl = &ls->dyd->gt;
	int i = ls->fs->bl->firstgoto;
	while (i < gl->n) {
		if (luaS_eqstr(gl->arr[i].name, lb->name))
			closegoto(ls, i, lb);
		else
			i++;
	}
}


/*
** "export" pending gotos to outer level, to check them against
** outer labels; if the block being exited has upvalues, and
** the goto exits the scope of any variable (which can be the
** upvalue), close those variables being exited.
*/
static void movegotosout (FuncState *fs, BlockCnt *bl) {
	int i = bl->firstgoto;
	Labellist *gl = &fs->ls->dyd->gt;
	/* correct pending gotos to current block and try to close it
	with visible labels */
	while (i < gl->n) {
		Labeldesc *gt = &gl->arr[i];
		if (gt->nactvar > bl->nactvar) {
			if (bl->upval)
				luaK_patchclose(fs, gt->pc, bl->nactvar);
			gt->nactvar = bl->nactvar;
		}
		if (!findlabel(fs->ls, i))
			i++;  /* move to next one */
	}
}


static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isloop) {
	bl->isloop = isloop;
	bl->nactvar = fs->nactvar;
	bl->firstlabel = fs->ls->dyd->label.n;
	bl->firstgoto = fs->ls->dyd->gt.n;
	bl->upval = 0;
	bl->previous = fs->bl;
	fs->bl = bl;
	lua_assert(fs->freereg == fs->nactvar);
}


/*
** create a label named "break" to resolve break statements
*/
static void breaklabel (LexState *ls) {
	TString *n = luaS_new(ls->L, "break");
	int l = newlabelentry(ls, &ls->dyd->label, n, 0, ls->fs->pc);
	findgotos(ls, &ls->dyd->label.arr[l]);
}

/*
** generates an error for an undefined 'goto'; choose appropriate
** message when label name is a reserved word (which can only be 'break')
*/
static l_noret undefgoto (LexState *ls, Labeldesc *gt) {
	const char *msg = isreserved(gt->name)
		? "<%s> at line %d not inside a loop"
		: "no visible label " LUA_QS " for <goto> at line %d";
	msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line);
	semerror(ls, msg);
}


static void leaveblock (FuncState *fs) {
	BlockCnt *bl = fs->bl;
	LexState *ls = fs->ls;
	if (bl->previous && bl->upval) {
		/* create a 'jump to here' to close upvalues */
		int j = luaK_jump(fs);
		luaK_patchclose(fs, j, bl->nactvar);
		luaK_patchtohere(fs, j);
	}
	if (bl->isloop)
		breaklabel(ls);  /* close pending breaks */
	fs->bl = bl->previous;
	removevars(fs, bl->nactvar);
	lua_assert(bl->nactvar == fs->nactvar);
	fs->freereg = fs->nactvar;  /* free registers */
	ls->dyd->label.n = bl->firstlabel;  /* remove local labels */
	if (bl->previous)  /* inner block? */
		movegotosout(fs, bl);  /* update pending gotos to outer block */
	else if (bl->firstgoto < ls->dyd->gt.n)  /* pending gotos in outer block? */
		undefgoto(ls, &ls->dyd->gt.arr[bl->firstgoto]);  /* error */
}


/*
** adds a new prototype into list of prototypes
*/
static Proto *addprototype (LexState *ls) {
	Proto *clp;
	lua_State *L = ls->L;
	FuncState *fs = ls->fs;
	Proto *f = fs->f;  /* prototype of current function */
	if (fs->np >= f->sizep) {
		int oldsize = f->sizep;
		luaM_growvector(L, f->p, fs->np, f->sizep, Proto *, MAXARG_Bx, "functions");
		while (oldsize < f->sizep) f->p[oldsize++] = NULL;
	}
	f->p[fs->np++] = clp = luaF_newproto(L);
	luaC_objbarrier(L, f, clp);
	return clp;
}


/*
** codes instruction to create new closure in parent function.
** The OP_CLOSURE instruction must use the last available register,
** so that, if it invokes the GC, the GC knows which registers
** are in use at that time.
*/
static void codeclosure (LexState *ls, expdesc *v) {
	FuncState *fs = ls->fs->prev;
	init_exp(v, VRELOCABLE, luaK_codeABx(fs, OP_CLOSURE, 0, fs->np - 1));
	luaK_exp2nextreg(fs, v);  /* fix it at the last register */
}


static void open_func (LexState *ls, FuncState *fs, BlockCnt *bl) {
	lua_State *L = ls->L;
	Proto *f;
	fs->prev = ls->fs;  /* linked list of funcstates */
	fs->ls = ls;
	ls->fs = fs;
	fs->pc = 0;
	fs->lasttarget = 0;
	fs->jpc = NO_JUMP;
	fs->freereg = 0;
	fs->nk = 0;
	fs->np = 0;
	fs->nups = 0;
	fs->nlocvars = 0;
	fs->nactvar = 0;
	fs->firstlocal = ls->dyd->actvar.n;
	fs->bl = NULL;
	f = fs->f;
	f->source = ls->source;
	f->maxstacksize = 2;  /* registers 0/1 are always valid */
	fs->h = luaH_new(L);
	/* anchor table of constants (to avoid being collected) */
	sethvalue2s(L, L->top, fs->h);
	incr_top(L);
	enterblock(fs, bl, 0);
}


static void close_func (LexState *ls) {
	lua_State *L = ls->L;
	FuncState *fs = ls->fs;
	Proto *f = fs->f;
	luaK_ret(fs, 0, 0);  /* final return */
	leaveblock(fs);
	luaM_reallocvector(L, f->code, f->sizecode, fs->pc, Instruction);
	f->sizecode = fs->pc;
	luaM_reallocvector(L, f->lineinfo, f->sizelineinfo, fs->pc, int);
	f->sizelineinfo = fs->pc;
	luaM_reallocvector(L, f->k, f->sizek, fs->nk, TValue);
	f->sizek = fs->nk;
	luaM_reallocvector(L, f->p, f->sizep, fs->np, Proto *);
	f->sizep = fs->np;
	luaM_reallocvector(L, f->locvars, f->sizelocvars, fs->nlocvars, LocVar);
	f->sizelocvars = fs->nlocvars;
	luaM_reallocvector(L, f->upvalues, f->sizeupvalues, fs->nups, Upvaldesc);
	f->sizeupvalues = fs->nups;
	lua_assert(fs->bl == NULL);
	ls->fs = fs->prev;
	/* last token read was anchored in defunct function; must re-anchor it */
	anchor_token(ls);
	L->top--;  /* pop table of constants */
	luaC_checkGC(L);
}



/*============================================================*/
/* GRAMMAR RULES */
/*============================================================*/


/*
** check whether current token is in the follow set of a block.
** 'until' closes syntactical blocks, but do not close scope,
** so it handled in separate.
*/
static int block_follow (LexState *ls, int withuntil) {
	switch (ls->t.token) {
	case TK_ELSE: case TK_ELSEIF:
	case TK_END: case TK_EOS:
		return 1;
	case TK_UNTIL: return withuntil;
	default: return 0;
	}
}


static void statlist (LexState *ls) {
	/* statlist -> { stat [`;'] } */
	while (!block_follow(ls, 1)) {
		if (ls->t.token == TK_RETURN) {
			statement(ls);
			return;  /* 'return' must be last statement */
		}
		statement(ls);
	}
}


static void fieldsel (LexState *ls, expdesc *v) {
	/* fieldsel -> ['.' | ':'] NAME */
	FuncState *fs = ls->fs;
	expdesc key;
	luaK_exp2anyregup(fs, v);
	luaX_next(ls);  /* skip the dot or colon */
	checkname(ls, &key);
	luaK_indexed(fs, v, &key);
}


static void yindex (LexState *ls, expdesc *v) {
	/* index -> '[' expr ']' */
	luaX_next(ls);  /* skip the '[' */
	expr(ls, v);
	luaK_exp2val(ls->fs, v);
	checknext(ls, ']');
}


/*
** {======================================================================
** Rules for Constructors
** =======================================================================
*/


struct ConsControl {
	expdesc v;  /* last list item read */
	expdesc *t;  /* table descriptor */
	int nh;  /* total number of `record' elements */
	int na;  /* total number of array elements */
	int tostore;  /* number of array elements pending to be stored */
};


static void recfield (LexState *ls, struct ConsControl *cc) {
	/* recfield -> (NAME | `['exp1`]') = exp1 */
	FuncState *fs = ls->fs;
	int reg = ls->fs->freereg;
	expdesc key, val;
	int rkkey;
	if (ls->t.token == TK_NAME) {
		checklimit(fs, cc->nh, MAX_INT, "items in a constructor");
		checkname(ls, &key);
	}
	else  /* ls->t.token == '[' */
		yindex(ls, &key);
	cc->nh++;
	checknext(ls, '=');
	rkkey = luaK_exp2RK(fs, &key);
	expr(ls, &val);
	luaK_codeABC(fs, OP_SETTABLE, cc->t->u.info, rkkey, luaK_exp2RK(fs, &val));
	fs->freereg = reg;  /* free registers */
}


static void closelistfield (FuncState *fs, struct ConsControl *cc) {
	if (cc->v.k == VVOID) return;  /* there is no list item */
	luaK_exp2nextreg(fs, &cc->v);
	cc->v.k = VVOID;
	if (cc->tostore == LFIELDS_PER_FLUSH) {
		luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);  /* flush */
		cc->tostore = 0;  /* no more items pending */
	}
}


static void lastlistfield (FuncState *fs, struct ConsControl *cc) {
	if (cc->tostore == 0) return;
	if (hasmultret(cc->v.k)) {
		luaK_setmultret(fs, &cc->v);
		luaK_setlist(fs, cc->t->u.info, cc->na, LUA_MULTRET);
		cc->na--;  /* do not count last expression (unknown number of elements) */
	}
	else {
		if (cc->v.k != VVOID)
			luaK_exp2nextreg(fs, &cc->v);
		luaK_setlist(fs, cc->t->u.info, cc->na, cc->tostore);
	}
}


static void listfield (LexState *ls, struct ConsControl *cc) {
	/* listfield -> exp */
	expr(ls, &cc->v);
	checklimit(ls->fs, cc->na, MAX_INT, "items in a constructor");
	cc->na++;
	cc->tostore++;
}


static void field (LexState *ls, struct ConsControl *cc) {
	/* field -> listfield | recfield */
	switch(ls->t.token) {
	case TK_NAME: {  /* may be 'listfield' or 'recfield' */
		if (luaX_lookahead(ls) != '=')  /* expression? */
			listfield(ls, cc);
		else
			recfield(ls, cc);
		break;
				  }
	case '[': {
		recfield(ls, cc);
		break;
			  }
	default: {
		listfield(ls, cc);
		break;
			 }
	}
}


static void constructor (LexState *ls, expdesc *t) {
	/* constructor -> '{' [ field { sep field } [sep] ] '}'
	sep -> ',' | ';' */
	FuncState *fs = ls->fs;
	int line = ls->linenumber;
	int pc = luaK_codeABC(fs, OP_NEWTABLE, 0, 0, 0);
	struct ConsControl cc;
	cc.na = cc.nh = cc.tostore = 0;
	cc.t = t;
	init_exp(t, VRELOCABLE, pc);
	init_exp(&cc.v, VVOID, 0);  /* no value (yet) */
	luaK_exp2nextreg(ls->fs, t);  /* fix it at stack top */
	checknext(ls, '{');
	do {
		lua_assert(cc.v.k == VVOID || cc.tostore > 0);
		if (ls->t.token == '}') break;
		closelistfield(fs, &cc);
		field(ls, &cc);
	} while (testnext(ls, ',') || testnext(ls, ';'));
	check_match(ls, '}', '{', line);
	lastlistfield(fs, &cc);
	SETARG_B(fs->f->code[pc], luaO_int2fb(cc.na)); /* set initial array size */
	SETARG_C(fs->f->code[pc], luaO_int2fb(cc.nh));  /* set initial table size */
}

/* }====================================================================== */



static void parlist (LexState *ls) {
	/* parlist -> [ param { `,' param } ] */
	FuncState *fs = ls->fs;
	Proto *f = fs->f;
	int nparams = 0;
	f->is_vararg = 0;
	if (ls->t.token != ')') {  /* is `parlist' not empty? */
		do {
			switch (ls->t.token) {
			case TK_NAME: {  /* param -> NAME */
				new_localvar(ls, str_checkname(ls));
				nparams++;
				break;
						  }
			case TK_DOTS: {  /* param -> `...' */
				luaX_next(ls);
				f->is_vararg = 1;
				break;
						  }
			default: luaX_syntaxerror(ls, "<name> or " LUA_QL("...") " expected");
			}
		} while (!f->is_vararg && testnext(ls, ','));
	}
	adjustlocalvars(ls, nparams);
	f->numparams = cast_byte(fs->nactvar);
	luaK_reserveregs(fs, fs->nactvar);  /* reserve register for parameters */
}


static void body (LexState *ls, expdesc *e, int ismethod, int line) {
	/* body ->  `(' parlist `)' block END */
	FuncState new_fs;
	BlockCnt bl;
	new_fs.f = addprototype(ls);
	new_fs.f->linedefined = line;
	open_func(ls, &new_fs, &bl);
	checknext(ls, '(');
	if (ismethod) {
		new_localvarliteral(ls, "self");  /* create 'self' parameter */
		adjustlocalvars(ls, 1);
	}
	parlist(ls);
	checknext(ls, ')');
	statlist(ls);
	new_fs.f->lastlinedefined = ls->linenumber;
	check_match(ls, TK_END, TK_FUNCTION, line);
	codeclosure(ls, e);
	close_func(ls);
}


static int explist (LexState *ls, expdesc *v) {
	/* explist -> expr { `,' expr } */
	int n = 1;  /* at least one expression */
	expr(ls, v);
	while (testnext(ls, ',')) {
		luaK_exp2nextreg(ls->fs, v);
		expr(ls, v);
		n++;
	}
	return n;
}


static void funcargs (LexState *ls, expdesc *f, int line) {
	FuncState *fs = ls->fs;
	expdesc args;
	int base, nparams;
	switch (ls->t.token) {
	case '(': {  /* funcargs -> `(' [ explist ] `)' */
		luaX_next(ls);
		if (ls->t.token == ')')  /* arg list is empty? */
			args.k = VVOID;
		else {
			explist(ls, &args);
			luaK_setmultret(fs, &args);
		}
		check_match(ls, ')', '(', line);
		break;
			  }
	case '{': {  /* funcargs -> constructor */
		constructor(ls, &args);
		break;
			  }
	case TK_STRING: {  /* funcargs -> STRING */
		codestring(ls, &args, ls->t.seminfo.ts);
		luaX_next(ls);  /* must use `seminfo' before `next' */
		break;
					}
	default: {
		luaX_syntaxerror(ls, "function arguments expected");
			 }
	}
	lua_assert(f->k == VNONRELOC);
	base = f->u.info;  /* base register for call */
	if (hasmultret(args.k))
		nparams = LUA_MULTRET;  /* open call */
	else {
		if (args.k != VVOID)
			luaK_exp2nextreg(fs, &args);  /* close last argument */
		nparams = fs->freereg - (base+1);
	}
	init_exp(f, VCALL, luaK_codeABC(fs, OP_CALL, base, nparams+1, 2));
	luaK_fixline(fs, line);
	fs->freereg = base+1;  /* call remove function and arguments and leaves
						   (unless changed) one result */
}




/*
** {======================================================================
** Expression parsing
** =======================================================================
*/


static void primaryexp (LexState *ls, expdesc *v) {
	/* primaryexp -> NAME | '(' expr ')' */
	switch (ls->t.token) {
	case '(': {
		int line = ls->linenumber;
		luaX_next(ls);
		expr(ls, v);
		check_match(ls, ')', '(', line);
		luaK_dischargevars(ls->fs, v);
		return;
			  }
	case TK_NAME: {
		singlevar(ls, v);
		return;
				  }
	default: {
		luaX_syntaxerror(ls, "unexpected symbol");
			 }
	}
}


static void suffixedexp (LexState *ls, expdesc *v) {
	/* suffixedexp ->
	primaryexp { '.' NAME | '[' exp ']' | ':' NAME funcargs | funcargs } */
	FuncState *fs = ls->fs;
	int line = ls->linenumber;
	primaryexp(ls, v);
	for (;;) {
		switch (ls->t.token) {
		case '.': {  /* fieldsel */
			fieldsel(ls, v);
			break;
				  }
		case '[': {  /* `[' exp1 `]' */
			expdesc key;
			luaK_exp2anyregup(fs, v);
			yindex(ls, &key);
			luaK_indexed(fs, v, &key);
			break;
				  }
		case ':': {  /* `:' NAME funcargs */
			expdesc key;
			luaX_next(ls);
			checkname(ls, &key);
			luaK_self(fs, v, &key);
			funcargs(ls, v, line);
			break;
				  }
		case '(': case TK_STRING: case '{': {  /* funcargs */
			luaK_exp2nextreg(fs, v);
			funcargs(ls, v, line);
			break;
				  }
		default: return;
		}
	}
}


static void simpleexp (LexState *ls, expdesc *v) {
	/* simpleexp -> NUMBER | STRING | NIL | TRUE | FALSE | ... |
	constructor | FUNCTION body | suffixedexp */
	switch (ls->t.token) {
	case TK_NUMBER: {
		init_exp(v, VKNUM, 0);
		v->u.nval = ls->t.seminfo.r;
		break;
					}
	case TK_STRING: {
		codestring(ls, v, ls->t.seminfo.ts);
		break;
					}
	case TK_NIL: {
		init_exp(v, VNIL, 0);
		break;
				 }
	case TK_TRUE: {
		init_exp(v, VTRUE, 0);
		break;
				  }
	case TK_FALSE: {
		init_exp(v, VFALSE, 0);
		break;
				   }
	case TK_DOTS: {  /* vararg */
		FuncState *fs = ls->fs;
		check_condition(ls, fs->f->is_vararg,
			"cannot use " LUA_QL("...") " outside a vararg function");
		init_exp(v, VVARARG, luaK_codeABC(fs, OP_VARARG, 0, 1, 0));
		break;
				  }
	case '{': {  /* constructor */
		constructor(ls, v);
		return;
			  }
	case TK_FUNCTION: {
		luaX_next(ls);
		body(ls, v, 0, ls->linenumber);
		return;
					  }
	default: {
		suffixedexp(ls, v);
		return;
			 }
	}
	luaX_next(ls);
}


static UnOpr getunopr (int op) {
	switch (op) {
	case TK_NOT: return OPR_NOT;
	case '-': return OPR_MINUS;
	case '#': return OPR_LEN;
	default: return OPR_NOUNOPR;
	}
}


static BinOpr getbinopr (int op) {
	switch (op) {
	case '+': return OPR_ADD;
	case '-': return OPR_SUB;
	case '*': return OPR_MUL;
	case '/': return OPR_DIV;
	case '%': return OPR_MOD;
	case '^': return OPR_POW;
	case TK_CONCAT: return OPR_CONCAT;
	case TK_NE: return OPR_NE;
	case TK_EQ: return OPR_EQ;
	case '<': return OPR_LT;
	case TK_LE: return OPR_LE;
	case '>': return OPR_GT;
	case TK_GE: return OPR_GE;
	case TK_AND: return OPR_AND;
	case TK_OR: return OPR_OR;
	default: return OPR_NOBINOPR;
	}
}


static const struct {
	lu_byte left;  /* left priority for each binary operator */
	lu_byte right; /* right priority */
} priority[] = {  /* ORDER OPR */
	{6, 6}, {6, 6}, {7, 7}, {7, 7}, {7, 7},  /* `+' `-' `*' `/' `%' */
	{10, 9}, {5, 4},                 /* ^, .. (right associative) */
	{3, 3}, {3, 3}, {3, 3},          /* ==, <, <= */
	{3, 3}, {3, 3}, {3, 3},          /* ~=, >, >= */
	{2, 2}, {1, 1}                   /* and, or */
};

#define UNARY_PRIORITY	8  /* priority for unary operators */


/*
** subexpr -> (simpleexp | unop subexpr) { binop subexpr }
** where `binop' is any binary operator with a priority higher than `limit'
*/
static BinOpr subexpr (LexState *ls, expdesc *v, int limit) {
	BinOpr op;
	UnOpr uop;
	enterlevel(ls);
	uop = getunopr(ls->t.token);
	if (uop != OPR_NOUNOPR) {
		int line = ls->linenumber;
		luaX_next(ls);
		subexpr(ls, v, UNARY_PRIORITY);
		luaK_prefix(ls->fs, uop, v, line);
	}
	else simpleexp(ls, v);
	/* expand while operators have priorities higher than `limit' */
	op = getbinopr(ls->t.token);
	while (op != OPR_NOBINOPR && priority[op].left > limit) {
		expdesc v2;
		BinOpr nextop;
		int line = ls->linenumber;
		luaX_next(ls);
		luaK_infix(ls->fs, op, v);
		/* read sub-expression with higher priority */
		nextop = subexpr(ls, &v2, priority[op].right);
		luaK_posfix(ls->fs, op, v, &v2, line);
		op = nextop;
	}
	leavelevel(ls);
	return op;  /* return first untreated operator */
}


static void expr (LexState *ls, expdesc *v) {
	subexpr(ls, v, 0);
}

/* }==================================================================== */



/*
** {======================================================================
** Rules for Statements
** =======================================================================
*/


static void block (LexState *ls) {
	/* block -> statlist */
	FuncState *fs = ls->fs;
	BlockCnt bl;
	enterblock(fs, &bl, 0);
	statlist(ls);
	leaveblock(fs);
}


/*
** structure to chain all variables in the left-hand side of an
** assignment
*/
struct LHS_assign {
	struct LHS_assign *prev;
	expdesc v;  /* variable (global, local, upvalue, or indexed) */
};


/*
** check whether, in an assignment to an upvalue/local variable, the
** upvalue/local variable is begin used in a previous assignment to a
** table. If so, save original upvalue/local value in a safe place and
** use this safe copy in the previous assignment.
*/
static void check_conflict (LexState *ls, struct LHS_assign *lh, expdesc *v) {
	FuncState *fs = ls->fs;
	int extra = fs->freereg;  /* eventual position to save local variable */
	int conflict = 0;
	for (; lh; lh = lh->prev) {  /* check all previous assignments */
		if (lh->v.k == VINDEXED) {  /* assigning to a table? */
			/* table is the upvalue/local being assigned now? */
			if (lh->v.u.ind.vt == v->k && lh->v.u.ind.t == v->u.info) {
				conflict = 1;
				lh->v.u.ind.vt = VLOCAL;
				lh->v.u.ind.t = extra;  /* previous assignment will use safe copy */
			}
			/* index is the local being assigned? (index cannot be upvalue) */
			if (v->k == VLOCAL && lh->v.u.ind.idx == v->u.info) {
				conflict = 1;
				lh->v.u.ind.idx = extra;  /* previous assignment will use safe copy */
			}
		}
	}
	if (conflict) {
		/* copy upvalue/local value to a temporary (in position 'extra') */
		OpCode op = (v->k == VLOCAL) ? OP_MOVE : OP_GETUPVAL;
		luaK_codeABC(fs, op, extra, v->u.info, 0);
		luaK_reserveregs(fs, 1);
	}
}


static void assignment (LexState *ls, struct LHS_assign *lh, int nvars) {
	expdesc e;
	check_condition(ls, vkisvar(lh->v.k), "syntax error");
	if (testnext(ls, ',')) {  /* assignment -> ',' suffixedexp assignment */
		struct LHS_assign nv;
		nv.prev = lh;
		suffixedexp(ls, &nv.v);
		if (nv.v.k != VINDEXED)
			check_conflict(ls, lh, &nv.v);
		checklimit(ls->fs, nvars + ls->L->nCcalls, LUAI_MAXCCALLS,
			"C levels");
		assignment(ls, &nv, nvars+1);
	}
	else {  /* assignment -> `=' explist */
		int nexps;
		checknext(ls, '=');
		nexps = explist(ls, &e);
		if (nexps != nvars) {
			adjust_assign(ls, nvars, nexps, &e);
			if (nexps > nvars)
				ls->fs->freereg -= nexps - nvars;  /* remove extra values */
		}
		else {
			luaK_setoneret(ls->fs, &e);  /* close last expression */
			luaK_storevar(ls->fs, &lh->v, &e);
			return;  /* avoid default */
		}
	}
	init_exp(&e, VNONRELOC, ls->fs->freereg-1);  /* default assignment */
	luaK_storevar(ls->fs, &lh->v, &e);
}


static int cond (LexState *ls) {
	/* cond -> exp */
	expdesc v;
	expr(ls, &v);  /* read condition */
	if (v.k == VNIL) v.k = VFALSE;  /* `falses' are all equal here */
	luaK_goiftrue(ls->fs, &v);
	return v.f;
}


static void gotostat (LexState *ls, int pc) {
	int line = ls->linenumber;
	TString *label;
	int g;
	if (testnext(ls, TK_GOTO))
		label = str_checkname(ls);
	else {
		luaX_next(ls);  /* skip break */
		label = luaS_new(ls->L, "break");
	}
	g = newlabelentry(ls, &ls->dyd->gt, label, line, pc);
	findlabel(ls, g);  /* close it if label already defined */
}


/* check for repeated labels on the same block */
static void checkrepeated (FuncState *fs, Labellist *ll, TString *label) {
	int i;
	for (i = fs->bl->firstlabel; i < ll->n; i++) {
		if (luaS_eqstr(label, ll->arr[i].name)) {
			const char *msg = luaO_pushfstring(fs->ls->L,
				"label " LUA_QS " already defined on line %d",
				getstr(label), ll->arr[i].line);
			semerror(fs->ls, msg);
		}
	}
}


/* skip no-op statements */
static void skipnoopstat (LexState *ls) {
	while (ls->t.token == ';' || ls->t.token == TK_DBCOLON)
		statement(ls);
}


static void labelstat (LexState *ls, TString *label, int line) {
	/* label -> '::' NAME '::' */
	FuncState *fs = ls->fs;
	Labellist *ll = &ls->dyd->label;
	int l;  /* index of new label being created */
	checkrepeated(fs, ll, label);  /* check for repeated labels */
	checknext(ls, TK_DBCOLON);  /* skip double colon */
	/* create new entry for this label */
	l = newlabelentry(ls, ll, label, line, fs->pc);
	skipnoopstat(ls);  /* skip other no-op statements */
	if (block_follow(ls, 0)) {  /* label is last no-op statement in the block? */
		/* assume that locals are already out of scope */
		ll->arr[l].nactvar = fs->bl->nactvar;
	}
	findgotos(ls, &ll->arr[l]);
}


static void whilestat (LexState *ls, int line) {
	/* whilestat -> WHILE cond DO block END */
	FuncState *fs = ls->fs;
	int whileinit;
	int condexit;
	BlockCnt bl;
	luaX_next(ls);  /* skip WHILE */
	whileinit = luaK_getlabel(fs);
	condexit = cond(ls);
	enterblock(fs, &bl, 1);
	checknext(ls, TK_DO);
	block(ls);
	luaK_jumpto(fs, whileinit);
	check_match(ls, TK_END, TK_WHILE, line);
	leaveblock(fs);
	luaK_patchtohere(fs, condexit);  /* false conditions finish the loop */
}


static void repeatstat (LexState *ls, int line) {
	/* repeatstat -> REPEAT block UNTIL cond */
	int condexit;
	FuncState *fs = ls->fs;
	int repeat_init = luaK_getlabel(fs);
	BlockCnt bl1, bl2;
	enterblock(fs, &bl1, 1);  /* loop block */
	enterblock(fs, &bl2, 0);  /* scope block */
	luaX_next(ls);  /* skip REPEAT */
	statlist(ls);
	check_match(ls, TK_UNTIL, TK_REPEAT, line);
	condexit = cond(ls);  /* read condition (inside scope block) */
	if (bl2.upval)  /* upvalues? */
		luaK_patchclose(fs, condexit, bl2.nactvar);
	leaveblock(fs);  /* finish scope */
	luaK_patchlist(fs, condexit, repeat_init);  /* close the loop */
	leaveblock(fs);  /* finish loop */
}


static int exp1 (LexState *ls) {
	expdesc e;
	int reg;
	expr(ls, &e);
	luaK_exp2nextreg(ls->fs, &e);
	lua_assert(e.k == VNONRELOC);
	reg = e.u.info;
	return reg;
}


static void forbody (LexState *ls, int base, int line, int nvars, int isnum) {
	/* forbody -> DO block */
	BlockCnt bl;
	FuncState *fs = ls->fs;
	int prep, endfor;
	adjustlocalvars(ls, 3);  /* control variables */
	checknext(ls, TK_DO);
	prep = isnum ? luaK_codeAsBx(fs, OP_FORPREP, base, NO_JUMP) : luaK_jump(fs);
	enterblock(fs, &bl, 0);  /* scope for declared variables */
	adjustlocalvars(ls, nvars);
	luaK_reserveregs(fs, nvars);
	block(ls);
	leaveblock(fs);  /* end of scope for declared variables */
	luaK_patchtohere(fs, prep);
	if (isnum)  /* numeric for? */
		endfor = luaK_codeAsBx(fs, OP_FORLOOP, base, NO_JUMP);
	else {  /* generic for */
		luaK_codeABC(fs, OP_TFORCALL, base, 0, nvars);
		luaK_fixline(fs, line);
		endfor = luaK_codeAsBx(fs, OP_TFORLOOP, base + 2, NO_JUMP);
	}
	luaK_patchlist(fs, endfor, prep + 1);
	luaK_fixline(fs, line);
}


static void fornum (LexState *ls, TString *varname, int line) {
	/* fornum -> NAME = exp1,exp1[,exp1] forbody */
	FuncState *fs = ls->fs;
	int base = fs->freereg;
	new_localvarliteral(ls, "(for index)");
	new_localvarliteral(ls, "(for limit)");
	new_localvarliteral(ls, "(for step)");
	new_localvar(ls, varname);
	checknext(ls, '=');
	exp1(ls);  /* initial value */
	checknext(ls, ',');
	exp1(ls);  /* limit */
	if (testnext(ls, ','))
		exp1(ls);  /* optional step */
	else {  /* default step = 1 */
		luaK_codek(fs, fs->freereg, luaK_numberK(fs, 1));
		luaK_reserveregs(fs, 1);
	}
	forbody(ls, base, line, 1, 1);
}


static void forlist (LexState *ls, TString *indexname) {
	/* forlist -> NAME {,NAME} IN explist forbody */
	FuncState *fs = ls->fs;
	expdesc e;
	int nvars = 4;  /* gen, state, control, plus at least one declared var */
	int line;
	int base = fs->freereg;
	/* create control variables */
	new_localvarliteral(ls, "(for generator)");
	new_localvarliteral(ls, "(for state)");
	new_localvarliteral(ls, "(for control)");
	/* create declared variables */
	new_localvar(ls, indexname);
	while (testnext(ls, ',')) {
		new_localvar(ls, str_checkname(ls));
		nvars++;
	}
	checknext(ls, TK_IN);
	line = ls->linenumber;
	adjust_assign(ls, 3, explist(ls, &e), &e);
	luaK_checkstack(fs, 3);  /* extra space to call generator */
	forbody(ls, base, line, nvars - 3, 0);
}


static void forstat (LexState *ls, int line) {
	/* forstat -> FOR (fornum | forlist) END */
	FuncState *fs = ls->fs;
	TString *varname;
	BlockCnt bl;
	enterblock(fs, &bl, 1);  /* scope for loop and control variables */
	luaX_next(ls);  /* skip `for' */
	varname = str_checkname(ls);  /* first variable name */
	switch (ls->t.token) {
	case '=': fornum(ls, varname, line); break;
	case ',': case TK_IN: forlist(ls, varname); break;
	default: luaX_syntaxerror(ls, LUA_QL("=") " or " LUA_QL("in") " expected");
	}
	check_match(ls, TK_END, TK_FOR, line);
	leaveblock(fs);  /* loop scope (`break' jumps to this point) */
}


static void test_then_block (LexState *ls, int *escapelist) {
	/* test_then_block -> [IF | ELSEIF] cond THEN block */
	BlockCnt bl;
	FuncState *fs = ls->fs;
	expdesc v;
	int jf;  /* instruction to skip 'then' code (if condition is false) */
	luaX_next(ls);  /* skip IF or ELSEIF */
	expr(ls, &v);  /* read condition */
	checknext(ls, TK_THEN);
	if (ls->t.token == TK_GOTO || ls->t.token == TK_BREAK) {
		luaK_goiffalse(ls->fs, &v);  /* will jump to label if condition is true */
		enterblock(fs, &bl, 0);  /* must enter block before 'goto' */
		gotostat(ls, v.t);  /* handle goto/break */
		skipnoopstat(ls);  /* skip other no-op statements */
		if (block_follow(ls, 0)) {  /* 'goto' is the entire block? */
			leaveblock(fs);
			return;  /* and that is it */
		}
		else  /* must skip over 'then' part if condition is false */
			jf = luaK_jump(fs);
	}
	else {  /* regular case (not goto/break) */
		luaK_goiftrue(ls->fs, &v);  /* skip over block if condition is false */
		enterblock(fs, &bl, 0);
		jf = v.f;
	}
	statlist(ls);  /* `then' part */
	leaveblock(fs);
	if (ls->t.token == TK_ELSE ||
		ls->t.token == TK_ELSEIF)  /* followed by 'else'/'elseif'? */
		luaK_concat(fs, escapelist, luaK_jump(fs));  /* must jump over it */
	luaK_patchtohere(fs, jf);
}


static void ifstat (LexState *ls, int line) {
	/* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */
	FuncState *fs = ls->fs;
	int escapelist = NO_JUMP;  /* exit list for finished parts */
	test_then_block(ls, &escapelist);  /* IF cond THEN block */
	while (ls->t.token == TK_ELSEIF)
		test_then_block(ls, &escapelist);  /* ELSEIF cond THEN block */
	if (testnext(ls, TK_ELSE))
		block(ls);  /* `else' part */
	check_match(ls, TK_END, TK_IF, line);
	luaK_patchtohere(fs, escapelist);  /* patch escape list to 'if' end */
}


static void localfunc (LexState *ls) {
	expdesc b;
	FuncState *fs = ls->fs;
	new_localvar(ls, str_checkname(ls));  /* new local variable */
	adjustlocalvars(ls, 1);  /* enter its scope */
	body(ls, &b, 0, ls->linenumber);  /* function created in next register */
	/* debug information will only see the variable after this point! */
	getlocvar(fs, b.u.info)->startpc = fs->pc;
}


static void localstat (LexState *ls) {
	/* stat -> LOCAL NAME {`,' NAME} [`=' explist] */
	int nvars = 0;
	int nexps;
	expdesc e;
	do {
		new_localvar(ls, str_checkname(ls));
		nvars++;
	} while (testnext(ls, ','));
	if (testnext(ls, '='))
		nexps = explist(ls, &e);
	else {
		e.k = VVOID;
		nexps = 0;
	}
	adjust_assign(ls, nvars, nexps, &e);
	adjustlocalvars(ls, nvars);
}


static int funcname (LexState *ls, expdesc *v) {
	/* funcname -> NAME {fieldsel} [`:' NAME] */
	int ismethod = 0;
	singlevar(ls, v);
	while (ls->t.token == '.')
		fieldsel(ls, v);
	if (ls->t.token == ':') {
		ismethod = 1;
		fieldsel(ls, v);
	}
	return ismethod;
}


static void funcstat (LexState *ls, int line) {
	/* funcstat -> FUNCTION funcname body */
	int ismethod;
	expdesc v, b;
	luaX_next(ls);  /* skip FUNCTION */
	ismethod = funcname(ls, &v);
	body(ls, &b, ismethod, line);
	luaK_storevar(ls->fs, &v, &b);
	luaK_fixline(ls->fs, line);  /* definition `happens' in the first line */
}


static void exprstat (LexState *ls) {
	/* stat -> func | assignment */
	FuncState *fs = ls->fs;
	struct LHS_assign v;
	suffixedexp(ls, &v.v);
	if (ls->t.token == '=' || ls->t.token == ',') { /* stat -> assignment ? */
		v.prev = NULL;
		assignment(ls, &v, 1);
	}
	else {  /* stat -> func */
		check_condition(ls, v.v.k == VCALL, "syntax error");
		SETARG_C(getcode(fs, &v.v), 1);  /* call statement uses no results */
	}
}


static void retstat (LexState *ls) {
	/* stat -> RETURN [explist] [';'] */
	FuncState *fs = ls->fs;
	expdesc e;
	int first, nret;  /* registers with returned values */
	if (block_follow(ls, 1) || ls->t.token == ';')
		first = nret = 0;  /* return no values */
	else {
		nret = explist(ls, &e);  /* optional return values */
		if (hasmultret(e.k)) {
			luaK_setmultret(fs, &e);
			if (e.k == VCALL && nret == 1) {  /* tail call? */
				SET_OPCODE(getcode(fs,&e), OP_TAILCALL);
				lua_assert(GETARG_A(getcode(fs,&e)) == fs->nactvar);
			}
			first = fs->nactvar;
			nret = LUA_MULTRET;  /* return all values */
		}
		else {
			if (nret == 1)  /* only one single value? */
				first = luaK_exp2anyreg(fs, &e);
			else {
				luaK_exp2nextreg(fs, &e);  /* values must go to the `stack' */
				first = fs->nactvar;  /* return all `active' values */
				lua_assert(nret == fs->freereg - first);
			}
		}
	}
	luaK_ret(fs, first, nret);
	testnext(ls, ';');  /* skip optional semicolon */
}


static void statement (LexState *ls) {
	int line = ls->linenumber;  /* may be needed for error messages */
	enterlevel(ls);
	switch (ls->t.token) {
	case ';': {  /* stat -> ';' (empty statement) */
		luaX_next(ls);  /* skip ';' */
		break;
			  }
	case TK_IF: {  /* stat -> ifstat */
		ifstat(ls, line);
		break;
				}
	case TK_WHILE: {  /* stat -> whilestat */
		whilestat(ls, line);
		break;
				   }
	case TK_DO: {  /* stat -> DO block END */
		luaX_next(ls);  /* skip DO */
		block(ls);
		check_match(ls, TK_END, TK_DO, line);
		break;
				}
	case TK_FOR: {  /* stat -> forstat */
		forstat(ls, line);
		break;
				 }
	case TK_REPEAT: {  /* stat -> repeatstat */
		repeatstat(ls, line);
		break;
					}
	case TK_FUNCTION: {  /* stat -> funcstat */
		funcstat(ls, line);
		break;
					  }
	case TK_LOCAL: {  /* stat -> localstat */
		luaX_next(ls);  /* skip LOCAL */
		if (testnext(ls, TK_FUNCTION))  /* local function? */
			localfunc(ls);
		else
			localstat(ls);
		break;
				   }
	case TK_DBCOLON: {  /* stat -> label */
		luaX_next(ls);  /* skip double colon */
		labelstat(ls, str_checkname(ls), line);
		break;
					 }
	case TK_RETURN: {  /* stat -> retstat */
		luaX_next(ls);  /* skip RETURN */
		retstat(ls);
		break;
					}
	case TK_BREAK:   /* stat -> breakstat */
	case TK_GOTO: {  /* stat -> 'goto' NAME */
		gotostat(ls, luaK_jump(ls->fs));
		break;
				  }
	default: {  /* stat -> func | assignment */
		exprstat(ls);
		break;
			 }
	}
	lua_assert(ls->fs->f->maxstacksize >= ls->fs->freereg &&
		ls->fs->freereg >= ls->fs->nactvar);
	ls->fs->freereg = ls->fs->nactvar;  /* free registers */
	leavelevel(ls);
}

/* }====================================================================== */


/*
** compiles the main function, which is a regular vararg function with an
** upvalue named LUA_ENV
*/
static void mainfunc (LexState *ls, FuncState *fs) {
	BlockCnt bl;
	expdesc v;
	open_func(ls, fs, &bl);
	fs->f->is_vararg = 1;  /* main function is always vararg */
	init_exp(&v, VLOCAL, 0);  /* create and... */
	newupvalue(fs, ls->envn, &v);  /* ...set environment upvalue */
	luaX_next(ls);  /* read first token */
	statlist(ls);  /* parse main body */
	check(ls, TK_EOS);
	close_func(ls);
}


Closure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
					  Dyndata *dyd, const char *name, int firstchar) {
						  LexState lexstate;
						  FuncState funcstate;
						  Closure *cl = luaF_newLclosure(L, 1);  /* create main closure */
						  /* anchor closure (to avoid being collected) */
						  setclLvalue(L, L->top, cl);
						  incr_top(L);
						  funcstate.f = cl->l.p = luaF_newproto(L);
						  funcstate.f->source = luaS_new(L, name);  /* create and anchor TString */
						  lexstate.buff = buff;
						  lexstate.dyd = dyd;
						  dyd->actvar.n = dyd->gt.n = dyd->label.n = 0;
						  luaX_setinput(L, &lexstate, z, funcstate.f->source, firstchar);
						  mainfunc(&lexstate, &funcstate);
						  lua_assert(!funcstate.prev && funcstate.nups == 1 && !lexstate.fs);
						  /* all scopes should be correctly finished */
						  lua_assert(dyd->actvar.n == 0 && dyd->gt.n == 0 && dyd->label.n == 0);
						  return cl;  /* it's on the stack too */
}

